SAN FRANCISCO – The U.S. Environmental Protection Agency is adding two new sites to the Superfund National Priorities List in California. The abandoned mine sites are located in San Benito and Siskiyou Counties.

Earlier this year, EPA proposed to add Northern California’s Blue Ledge mine site and Central California’s New Idria mercury mine site to the Superfund National Priorities List because of the toxic pollutants discharged by both to California’s waterways. With today’s action, these two sites are now finalized on the Superfund NPL. Superfund is the federal program that investigates and cleans up the most complex, uncontrolled or abandoned hazardous waste sites in the country.

The New Idria Mercury Mine site in San Benito County affects waterways leading to the San Joaquin River and San Francisco Bay. The Blue Ledge Mine in Siskiyou County discharges into streams in the Rogue River-Siskiyou National Forest and ultimately the Applegate Reservoir, a popular recreation area.

“The legacy of abandoned mines continues to threaten the public health and natural resources of California,” said Jared Blumenfeld, EPA’s Regional Administrator for the Pacific Southwest. “Now that these toxic mines sites have been declared Superfund sites, the EPA can move ahead to clean them up, protecting important waterways like the San Francisco Bay from mercury and other pollutants.”

New Idria was the second largest producer of mercury in North America and was in operation more than 100 years. The abandoned mercury mine is located approximately 64 miles southeast of Hollister, Calif. The mine served as the primary processing point for mercury mines in the larger New Idria Mining District. Past mining operations have resulted in mercury contamination and acid mine drainage in San Carlos Creek, Silver Creek and a portion of Panoche Creek, at levels toxic to aquatic organisms. Environmental impacts extend more than fifteen miles to creeks and wetland areas, endangered species habitat, and potentially the San Joaquin River and the San Francisco Bay. Mercury is toxic and bioaccumulates in living organisms. It can cause both chronic and acute poisoning. Methylmercury, an organic compound derived from mercury, is highly toxic and is associated with live aquatic systems such as the wetlands and sediments found down gradient from New Idria.

The Blue Ledge Mine is located on privately owned land surrounded by the Rogue River-Siskiyou National Forest, approximately three miles south of the Oregon-California border. Past copper and zinc mining operations, copper, cadmium, other metals, and acid mine drainage have contaminated sediments and surface water at levels that are toxic to aquatic organisms. Impacts include the absence of fish for more than three miles downstream and potential negative impacts to fisheries all the way to the Applegate Reservoir, a popular recreational area.

In 2006 the EPA performed an emergency response action to stabilize waste rock that was releasing into Joe Creek, just downstream from the mine. In 2010, the U.S. Forest Service (USFS) received $12.4 million in American Reinvestment and Recovery Act funds plus $1.4 million from the ASARCO Environmental Trust to place the waste rock into an on-site repository. This work began last summer. Superfund listing of the site will allow completion of the cleanup.

EPA also announced that it is proposing to add to the NPL two industrial facilities that have contaminated the local groundwater resources in Southern California. The Seam Master Industries site and the Jervis B. Webb Co site are both located in South Gate, California, in Los Angeles County. Volatile organic compounds, including elevated levels of trichloroethylene, have been confirmed in the soils and ground water at both of these sites. Trichloroethylene is commonly used as a solvent for cleaning metal parts.

To date, there have been 1,652 sites listed on the NPL since 1980, 107 of which are in California. Nationally, cleanups have been completed at two-thirds of these sites.

With all Superfund sites, EPA tries to identify and locate the parties potentially responsible for the contamination. For the newly listed sites without viable potentially responsible parties, EPA will investigate the full extent of the contamination before starting significant cleanup at the site.